1. Technical Field
The invention relates to a phenolic resin molding compound.
2. Related Art
Hitherto, there has been a demand for heat resistance and abrasion resistance in mechanical parts that are used in vehicles and the like. As a material that satisfies these characteristics, parts formed from ceramic or metal have been used in mechanical parts in the related art. However, the mechanical parts formed from ceramic or metal have various problems in that the weight thereof is heavy, it takes a long time for processing, the cost is high, and the like. As means for solving these problems, mechanical parts formed from plastic material have attracted attention from a viewpoint of weight reduction of the parts.
As a material that is used in the case of forming the mechanical parts, among plastic materials, particularly, a phenolic resin molding compound has attracted attention from a viewpoint of heat resistance or abrasion resistance. The mechanical parts that include the phenolic resin molding compound are superior in that the weight thereof is lighter, processing is easier, and heat resistance is higher compared to mechanical parts formed from ceramic or metal. In addition, to give heat resistance and mechanical strength to the mechanical parts, glass fiber, silica, or the like has been used as a filling material in the related art. However, in the case of forming the mechanical parts using the phenolic resin molding compound, when the filling material such as the glass fiber and silica is used, the mechanical strength is improved, but there is a problem in that the abrasion resistance deteriorates. Therefore, in a case where the abrasion resistance is an important characteristic, the phenolic resin molding compound that is inferior in abrasion resistance may not be used. In addition, in a case where the mechanical parts are molded using the phenolic resin molding compound, since dimensional change may easily occur, there is a problem in that the dimensions of the mechanical parts are not maintained within a tolerance, and a yield ratio deteriorates.
A precision part may absorb moisture and swell, such that operation failure may be caused. Therefore, it is necessary to make dimensional stability under high humidity excellent.
As technologies of improving an abrasion characteristic and water resistance of a mechanism part that is molded using a phenolic resin molding compound, technologies described in Japanese Unexamined Patent Publication Nos. 2005-47971, 2005-265033, and 2011-68705 have been disclosed.
Japanese Unexamined Patent Publication No. 2005-47971 discloses a technology of improving an abrasion characteristic by blending graphite that is a solid lubricant to a phenolic resin molding compound.
Japanese Unexamined Patent Publication No. 2005-265033 discloses a technology of improving an abrasion characteristic and a mechanical characteristic by using glass fiber in combination in addition to graphite. In the technology disclosed in Japanese Unexamined Patent Publication No. 2005-265033, in regard to contents of the graphite and glass fiber on the basis of the entirety of the molding compound, the content of the graphite is 5 to 20% by weight and the content of the glass fiber is 40 to 60% by weight.
Japanese Unexamined Patent Publication No. 2011-68705 discloses a technology of improving dimensional accuracy and dimensional stability with heat resistance and moisture resistance by blending an alkylbenzene-modified novolac-type phenolic resin and glass fiber. In the technology disclosed in Japanese Unexamined Patent Publication No. 2011-68705, on the basis of the entirety of the molding compound, a total content of (A) a novolac-type phenolic resin including the alkylbenzene-modified novolac-type phenolic resin, (B) a resol-type phenolic resin, and (C) hexamethylenetetramine is 15 to 30% by weight, and a content of the glass fiber is 10 to 20% by weight.